D-Link DES-3326SR User Manual page 136

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
The rest of the packet consists of a list of the topological
database's pieces. Each link state advertisement in the
database is described by its link state advertisement header.
The Link-State Request Packet
Link-State Request packets are OSPF packet type 3. After
exchanging Database Description packets with a neighboring
router, a router may find that parts of its topological database
are out of date. The Link-State Request packet is used to
request the pieces of the neighbor's database that are more up
to date. Multiple Link-State Request packets may need to be
used. The sending of Link-State Request packets is the last
step in bringing up an adjacency.
A router that sends a Link-State Request packet has in mind
the precise instance of the database pieces it is requesting,
defined by LS sequence number, LS checksum, and LS age,
although these fields are not specified in the Link-State
Request packet itself. The router may receive even more recent
instances in response.
The format of the Link-State Request packet is shown below:
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